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authorPeter Zijlstra <peterz@infradead.org>2017-04-10 12:47:33 +0200
committerIngo Molnar <mingo@kernel.org>2017-04-14 10:26:36 +0200
commit3841cdc31099fe3b84c93903c63e3d60348c0ea1 (patch)
treefbf5cfbe5db805f191b8be1afe7d2dc78399fdbe /kernel/sched
parent76d034edcf658e3c74fd90b149882ab1464e4af9 (diff)
downloadop-kernel-dev-3841cdc31099fe3b84c93903c63e3d60348c0ea1.zip
op-kernel-dev-3841cdc31099fe3b84c93903c63e3d60348c0ea1.tar.gz
sched/fair: Fix comments
Historically our periods (or p) argument in PELT denoted the number of full periods (what is now d2). However recent patches have changed this to the total decay (previously p+1), leading to a confusing discrepancy between comments and code. Try and clarify things by making periods (in code) and p (in comments) be the same thing (again). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c20
1 files changed, 10 insertions, 10 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1e5f580..d43e9ac 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2777,18 +2777,18 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
u32 c1, c2, c3 = d3; /* y^0 == 1 */
/*
- * c1 = d1 y^(p+1)
+ * c1 = d1 y^p
*/
c1 = decay_load((u64)d1, periods);
/*
- * p
+ * p-1
* c2 = 1024 \Sum y^n
* n=1
*
* inf inf
* = 1024 ( \Sum y^n - \Sum y^n - y^0 )
- * n=0 n=p+1
+ * n=0 n=p
*/
c2 = LOAD_AVG_MAX - decay_load(LOAD_AVG_MAX, periods) - 1024;
@@ -2808,15 +2808,15 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
* |<->|<----------------->|<--->|
* ... |---x---|------| ... |------|-----x (now)
*
- * p
- * u' = (u + d1) y^(p+1) + 1024 \Sum y^n + d3 y^0
- * n=1
+ * p-1
+ * u' = (u + d1) y^p + 1024 \Sum y^n + d3 y^0
+ * n=1
*
- * = u y^(p+1) + (Step 1)
+ * = u y^p + (Step 1)
*
- * p
- * d1 y^(p+1) + 1024 \Sum y^n + d3 y^0 (Step 2)
- * n=1
+ * p-1
+ * d1 y^p + 1024 \Sum y^n + d3 y^0 (Step 2)
+ * n=1
*/
static __always_inline u32
accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
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